1. Field of Invention
This invention relates to a method and an apparatus for improving the quality of a printed image. In particular, the invention relates to a method and apparatus for automatically determining a gamma (.gamma.) of an image, and for adjusting the .gamma. of a printer to improve the quality of the printed image.
2. Description of Related Art
More and more documents are created in an electronic form. Many of these documents are created with the initial intent that they remain electronic, such as Web sites for personal, commercial, or business use. These electronic documents often contain images that are of a "frame-worthy" quality. That is, in terms of photographic content and quality, the images are good enough to use as a framed picture.
However, when these images are printed, the resulting print may be of inferior quality. The reason for this inferior quality is the difference of the reproduction behavior of a CRT monitor and a color printer, or, more generally, the difference between the intended and the actual output device. A major difference between the output devices is the device gamma (hereinafter, .gamma.), and consequently, the image processing that was performed to optimize the image for the originally intended device .gamma.. Displaying or printing that image on a device with a different .gamma. will lead to unacceptable image deterioration. For example, electronic images may be designed with a .gamma. of approximately two, which is commensurate for displaying the image on a cathode ray tube, for example. The cathode ray tube may be incorporated into a personal computer or a television, for example. However, if the image is then printed on a printer, the quality of the resulting image may be poor because the .gamma. of the printer is typically chosen to be approximately 1. As a result, the printed color image is often "washed-out" or pale.
To obtain high quality original color images, the .gamma. of the printer should be adjusted to correspond to that of the image (i.e., .gamma..apprxeq.2). However, current systems are not capable of determining the .gamma. of an image when the image is viewed from an electronic document. Accordingly, an improved method and apparatus are needed to automatically determine the .gamma. of a color image that is incorporated into an electronic document, and to adjust the .gamma. setting of the printer to achieve optimum image quality.